Flame retardant polycarbonate compositions

ABSTRACT

Improved non-opque flame retardant compositions comprised of, in admixture: 
     (i) at least one aromatic polycarbonate resin derived from (a) at least one halogen-free and sulfur-free dihydric phenol, (b) a minor amount of at least one halogen-free thiodiphenol, and (c) a carbonate precursor; and 
     (ii) a minor amount of at least one organic alkali or alkaline earth metal salt of sulfonic acid.

BACKGROUND OF THE INVENTION

The increasing concern for safety has resulted in a move towardsproviding safer materials for public and household use. A particulararea of need is that of providing flame retardant products which are nowrequired to meet certain flame retardant criteria by both local andfederal governments as well as by manufacturers of such products. Oneparticular set of conditions used as a standard for flame retardancy isset forth in Underwriters' Laboratories, Inc. Bulletin 94 which setsforth certain conditions by which materials are rated forself-extinguishing or flame retardant characteristics.

It is known that various halogen-containing and sulfur-containing flameretardant additives can be employed to render plastic productsself-extinguishing or flame retardant. Such flame retardant additivesare typically employed in amounts sufficient to be effective for theirintended purpose; generally on the order of 5-20 weight percent basedupon the weight of the plastic compositions. In many instances the useof these flame retardant additives in such amounts can have a degradingeffect upon the plastic compositions to be rendered flame retardant,often resulting in the deterioration of valuable physical properties ofthe base polymers. This is particularly so when known flame retardantadditives are employed with polycarbonate resins since many of theseadditives have a deleterious effect upon the carbonate polymer,typically resulting in discoloration, loss of impact strength, and lossof clarity and/or transparency.

It is known that polycarbonates based on halogen-containing diphenolsand thiodiphenols, and blends of halogen-free polycarbonates based ondiphenols and thiodiphenols with halogen containing diphenols are flameretardant, as disclosed in U.S. Pat. Nos. 4,043,980 and 4,174,359.However, the side effects of the halogen-containing polycarbonates suchas the high processing temperatures necessary to obtain molded products,and the adverse effects on impact strength, particularly thick sectionimpact strength, seriously limit the applications of such halogencontaining polycarbonate compositions.

It is also known to provide flame retardant polycarbonate compositionsby admixing with the polycarbonate resin certain organic alkali andalkaline earth metal salts of sulfonic acids. Such flame retardantcompositions are disclosed in U.S. Pat. Nos. 3,909,490; 3,917,559;3,919,167; 3,926,908; 3,933,734; 3,940,366; 3,951,910; 3,953,396;3,953,399 and 3,978,024. While these compositions have proved to bequite effective and useful in most applications they suffer from thedisadvantage that in some instances, particularly if some of these saltsare used in relatively large concentrations, e.g., approaching the 5-10%levels, which range is within the 0.01-10% range disclosed by theaforementioned patents, they tend to adversely impact upon the opticaltransparency of the polycarbonate compositions.

It is also known, as disclosed in copending application Ser. No.347,484, filed on Feb. 10, 1982 that polycarbonate compositions can berendered flame retardant by either admixing with the carbonate polymer apolymer based on a thiodiphenol, or incorporating into the polycarbonatebackbone a thiodiphenol residue. While these compositions are also quiteeffective and useful in most applications, they suffer from thedisadvantage that relatively quite large amounts of thiodiphenol,typically from about 23-98 mole percent, must be employed to render saidcompositions flame retardant. Since thiodiphenol is relativelyexpensive, as compared with dihydric phenols such as bisphenol-A, itsuse, particularly at the upper concentration ranges, places these flameretardant polycarbonate compositions at an economic disadvantage.Secondly, in some applications, particularly those where thepolycarbonate resin is required to exhibit properties of sulfur-freebisphenols such as bisphenol-A, such large concentrations ofthiiodiphenol are undesirable.

It would thus be very advantageous if a flame retardant polycarbonatecomposition could be provided which exhibited substantially most of theadvantageous properties of sulfur-free and halogen-free polycarbonates,such as for example, good impact strength, particularly good thicksection impact strength, optical transparency, and good processability,while at the same time being economically competitive. It is, therefore,an object of the instant invention to provide such a flame retardantpolycarbonate composition.

It has been discovered that employing minor amounts of the organicalkali or alkaline earth metal salts of sulfonic acids with apolycarbonate resin derived from a dihydric phenol and minor amounts ofa thiodiphenol results in a flame retardant polycarbonate compositionwhich exhibits, to a substantial degree, substantially most of theadvantageous properties of unmodified polycarbonate resins, such as forexample, good impact strength, particularly good thick section impactstrength, ease of processability, and optical transparency, whilesimultaneously being economically competitive with unmodified dihydricphenol based polycarbonate compositions.

SUMMARY OF THE INVENTION

Improved flame retardant polycarbonate compositions exhibiting opticaltransparency and good impact strength, particularly good thick sectionimpact strength, comprised of, in admixture: (i) at least onehalogen-free carbonate polymer derived from (a) at least onenon-polycyclic, halogen-free and sulfur-free dihydric phenol; (b) aminor amount of at least one halogen-free thiodiphenol; and (ii) a minoramount of at least one organic metal salt of sulfonic acid selected fromthe organic alkali and alkaline earth metal salts of sulfonic acids.

DESCRIPTION OF THE INVENTION

It has now been discovered that the flammability of polycarbonate resincompositions containing a halogen-free polycarbonate can be dramaticallyimproved without deleteriously affecting, to a substantial degree, anyof the other advantageous physical and mechanical properties of thepolycarbonate resin such as, for example, the impact strength,particularly the thick section impact strength, the processability, andthe optical transparency. This can be accomplished by (i) incorporatinginto the polycarbonate resin compositions, either chemically into thebackbone of said halogen-free polycarbonate resin, or physically as aseparate polymer into the composition, a minor amount of at least onehalogen-free thiodiphenol; and (ii) physically admixing with saidhalogen-free polycarbonate resin a minor amount of at least one organicmetal salt of sulfonic acid selected from the organic alkali andalkaline earth metal salts of sulfonic acids.

This dramatic improvement in flame retardancy of these polycarbonatecompositions is believed to be due to the synergism between the sulfurpresent in the form of the thiodiphenol residue and the alkali andalkaline earth metal salts of sulfonic acids.

Furthermore, not only do the instant compositions exhibit improved flameretardancy, but they also exhibit good impact strength and retainsubstantially most of the other valuable properties of unmodifiedpolycarbonate resins such as optical clarity, toughness flexibility, andhigh heat distortion temperatures.

In one embodiment of this invention the thiodiphenol residue ischemically combined with the halogen-free carbonate resin present in theinstant compositions. In this embodiment the polycarbonate compositionscontain, in admixture: (i) at least one halogen-free and sulfurcontaining polycarbonate resin comprised of the coreaction products of(a) at least one non-polycyclic, halogen-free and sulfur-free dihydricphenol (b) at least one halogen-free thiodiphenol, and (c) a carbonateprecursor; and (ii) a minor amount of at least one organic metal salt ofsulfonic acid selected from alkali and alkaline earth metal salts oforganic sulfonic acids.

The non-polycyclic halogen-free and sulfur-free dihydric phenols usefulin the instant invention are represented by the general formula ##STR1##wherein: R is independently selected from monovalent hydrocarbonradicals;

R' is independently selected from monovalent hydrocarbon radicals;

E is selected from non-cyclic divalent hydrocarbon radicals, mono-cyclicdivalent hydrocarbon radicals, the --O-- radicals, and the ##STR2##radical; n and n' are independently selected from whole numbers having avalue of from 0 to 4 inclusive; and

p is either one or zero.

The monovalent hydrocarbon radicals represented by R and R' are selectedfrom alkyl, aryl, aralkyl, and alkaryl radicals. Preferred alkylradicals represented by R and R' are those containing from 1 to 12carbon atoms. Some illustrative non-limiting examples of these alkylradicals include methyl, ethyl, propyl, isopropyl, butyl, tertiarybutyl, pentyl, neopentyl, etc.

The aryl radicals are those containing one aromatic ring, i.e., thephenyl radical.

Preferred aralkyl and alkaryl radicals represented by R and R' are thosecontaining one aromatic ring and from 7 to 11 carbon atoms, e.g.,benzyl, ethylphenyl, propylphenyl, and the like.

The non-cyclic divalent hydrocarbon radicals represented by E areselected from alkylene and alkylidene radicals.

The preferred alkylene and alkylidene radicals represented by E arethose containing from 1 to about 12 carbon atoms. Some illustrativenon-limiting examples of these alkylene and alkylidene radicals includemethylene, ethylene, propylene, 1,2-propylene, propylidene,isopropylidene, butylene, 2-methyl-1,3-propylene, butylidene,isobutylidene, and the like.

The monocylic divalent hydrocarbon radicals represented by E areselected from cycloalkylene and cycloalkylidene radicals. Preferredcycloalkylene and cycloalkylidene radicals are those containing from 4to about 16 carbon atoms in the cyclic structure. These preferredcycloalkylene and cycloalkylidene radicals may be represented by thegeneral formula ##STR3## wherein: R¹ is independently selected fromlower alkyl radicals, preferably those containing from 1 to about 5carbon atoms;

Z is a cycloalkylene or cycloalkylidene containing from 4 to 16 carbonatoms in the monocyclic structure; and

d is a whole number having a value of from 0 up to and including thenumber of replaceable hydrogen atoms present on Z, preferably d has avalue of from 0 to 6 inclusive.

Some illustrative, non-limiting examples of these preferredcycloalkylene and cycloalkylidene radicals include, cyclopentylene,cyclopentylidene, cyclohexylene, cyclohexylidene, methylcyclohexylene,ethylcyclohexylidene, and the like.

In the dihydric phenol compound represented by Formula I, when more thanone R substituent is present they may be the same or different. The sameis true for the R' substituent. Where p is zero in Formula I thearomatic rings are directly joined with no intervening alkylene or otherbridge. The positions of the hydroxyl groups and R or R' on the aromaticnuclear residues can be varied in the ortho, meta, or para positions andthe groupings can be in a vicinal, asymmetrical or symmetricalrelationship, where two or more ring carbon atoms of the aromatichydrocarbon residues are substituted with R or R' and hydroxyl group.

Preferred R and R' substituents are the alkyl radicals, with the loweralkyl radicals containing from 1 to about 5 carbon atoms beingpreferred.

Some illustrative non-limiting examples of the dihydric phenols ofFormula V include:

2,2-bis(4-hydroxyphenyl)propane (bisphenol-A);

2,4'-dihydroxydiphenylmethane;

bis(2-hydroxyphenyl)methane;

bis(4-hydroxyphenyl)methane;

1,1-bis(4-hydroxyphenyl)ethane;

1,2-bis(4-hydroxyphenyl)ethane;

1,1-bis(2,5-dimethyl-4-hydroxyphenyl)ethane;

1,3-bis(3-methyl-4-hydroxyphenyl)propane;

2,2-bis(3-isopropyl-5-ethyl-4-hydroxyphenyl)propane;

2,2-bis(3-isopropyl-4-hydroxyphenyl)propane;

2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane;

2,2-bis(3-methyl-5-ethyl-4-hydroxyphenyl)propane;

3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl

1,4-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane;

1,4-bis(4-hydroxyphenyl)cyclohexane;

1,1-bis(4-hydroxyphenyl)cyclohexane;

4,4'-dihydroxy-2,6-dimethyldiphenyl ether;

4,4'-dihydroxy-3,3'-diisopropylidiphenyl ether; and the like.

The halogen-free thiodiphenols useful in the practice of the instantinvention are represented by the general formula ##STR4## wherein: R² isindependently selected from monovalent hydrocarbon radicals;

R³ is independently selected from monovalent hydrocarbon radicals; and

c and c' are independently selected from whole numbers having a value offrom 0 to 4 inclusive.

The monovalent hydrocarbon radicals represented by R² and R³ areselected from alkyl, aryl, alkaryl, and aralkyl radicals.

Preferred alkyl radicals are those containing from 1 to about 6 carbonatoms.

The preferred aryl radical is the phenyl radical.

Preferred aralkyl and alkaryl radicals are those containing from 7 toabout 11 carbon atoms.

Preferred monovalent hydrocarbon radicals represented by R² and R³ arethe alkyl radicals, with alkyl radicals containing from 1 to about 5carbon atoms being the preferred alkyl radicals.

In the thiodiphenol compounds of Formula III when more than one R²substituent is present they may be the same or different. The same istrue for the R³ substituent. The positions of R² or R³ and the hydroxylgroups on the aromatic nuclear residues can be varied in the ortho, eta,or para positions and the groupings can be in a vicinal, asymmetrical orsymmetrical relationship, where two or more ring carbon atoms of thearomatic hydrocarbon residues are substituted with R² or R³ and hydroxylgroup.

Some illustrative non-limiting examples of the halogen-free thiodiphenolof Formula III include:

2-methyl-4,4'-thiodiphenol;

2,2'-dimethyl-4,4'-thiodiphenol;

2,2-di-tertiarybutyl-4,4'-thiodiphenol;

2,2',3,3',5,5',6,6'-octamethyl-4,4'-thiodiphenol;

3,3'-dimethyl-4,4'-thiodiphenol;

3-methyl-3'-ethyl-4,4'-thiodiphenol;

3,3'-dimethyl-4,4'-thiodiphenol;

2,2',3,3',5,5'-hexaethyl-4,4'-thiodiphenol;

2-methyl-3-propyl-4,4'-thiodiphenol;

3,5-dimethyl-4,4'-thiodiphenol;3,5-dimethyl-3'-propyl-4,4'-thiodiphenol;

3,3',5,5'-tetramethyl-4,4'-thiodiphenol;

2,2',3,3',5,5'-hexabutyl-4,4'-thiodiphenol;

2,3,5,6'-tetrapropyl-4,4'-thiodiphenol; and the like.

These thiodiphenols are utilized in minor amounts. By minor amounts ismeant that the predominate residue present in the polycarbonate resin isthe dihydric phenol residue.

Quite useful thiodiphenols of Formula III are the 4,4'-thiodiphenols.

Particularly useful halogen-free thiodiphenols of Formula III are the3,3',5,5'-tetraalkyl-4,4'-thiodiphenols such as, for example:

3,3',5,5'-tetramethyl-4,4'-thiodiphenol;

3,3',5,5'-tetraethyl-4,4'-thiodiphenol;

3,3'-dimethyl-5,5'-diethyl-4,4'-thiodiphenol;

3,5-diethyl-3',5'-dipropyl-4,4'-thiodiphenol; and the like.

It is of course possible to employ mixtures of two or more differentdihydric phenols of Formula I or two or more different thiodiphenols ofFormula III; or a dihydric phenol and/or a thiodiphenol with a glycol,or with a hydroxy or acid terminated polyester, or with a dibasic acidin the event a carbonate copolymer, terpolymer, interpolymer, or acopolyester-carbonate polymer is desired for use in the preparation ofthe aromatic carbonate polymer compositions of the instant invention.

The halogen-free and sulfur-containing non-polycyclic carbonate resinsuseful in the instant invention are prepared by coreacting, as essentialingredients, (i) at least one dihydric phenol of Formula I; (ii) atleast one thiodiphenol of Formula III; and (iii) a carbonate precursor.

The carbonate precursor may be a carbonyl halide, a carbonate ester, ora haloformate. The carbonyl halides which may be employed are carbonylbromide, carbonyl chloride and mixtures thereof. Typical of thecarbonate esters which can be employed are diphenyl carbonate;di-(alkylphenyl)carbonates such as di(tolyl)carbonate etc.:di-(naphthyl)carbonate; phenyl tolyl carbonate, etc., or mixturesthereof. The haloformates which can be used include bis-haloformates ofthe dihydric phenols employed, including both the sulfur-free andsulfur-containing (thiodiphenols) diphenols employed, such asBPA-bis(chloroformate) and thiodiphenol bis(chloroformate) and theircongeners. While other carbonate precursors will occur to those skilledin the art, carbonyl chloride, also known as phosgene, is preferred.

One method which may be utilized in preparing the polycarbonates of theinstant invention involves the heterogeneous interfacial polymerizationsystem utilizing an aqueous caustic solution, an organic waterimmiscible solvent, at least one dihydric phenol of Formula I, at leastone thiodiphenol of Formula III, a catalyst, a carbonate precursor, anda molecular weight regulator. A preferred heterogeneous interfacialpolymerization system is one which uses phosgene as a carbonateprecursor.

Another useful method for preparing the carbonate polymers of theinstant invention involves the use of an organic solvent system whereinthe organic solvent system may also function as the acid acceptor, atleast one dihydric phenol of Formula I, at least one thiodiphenol ofFormula III, a molecular weight regulator, and a carbonate precursor. Apreferred method is one wherein phosgene is employed as the carbonateprecursor.

Generally, in both of the aforediscussed methods phosgene is passed intothe reaction mixture containing at least one dihydric phenol of FormulaI and at least one thiodiphenol of Formula III. The temperature at whichthe phosgenation reaction proceeds may vary from below 0° C. to above100° C. The reaction proceeds satisfactorily at temperatures from roomtemperature (25° C.) to about 50° C. Since the reaction is exothermic,the rate of phosgene addition may be used to control the reactiontemperature.

The acid acceptor may be either an organic or an inorganic acidacceptor. A suitable organic acid acceptor is a tertiary amine andincludes such materials as pyridine, triethylamine dimethylaniline,tributylamine, etc. The inorganic acid acceptor can be one which can bea hydroxide, a carbonate, a bicarbonate, or a phosphate of an alkali oralkaline earth metal.

The catalysts which can be employed are any of the catalysts that aidthe polymerization of the diphenol such as bisphenol-A with phosgene.Suitable catalysts include, but are not limited to, tertiary amines suchas, for example, triethylamine, tripropylamine, N,N-dimethylaniline,quaternary ammonium compounds such as, for example, tetraethylammoniumbromide, cetyl triethylammonium bromide, tetra-n-heptylammonium iodide,and the like.

The molecular weight regulators employed may be any of the knowncompounds which regulate the molecular weight of the carbonate polymersby a chain stopping or terminating mechanism. These compounds include,but are not limited to, phenol, tertiarybutyl phenol, and the like.

Also included herein are branched polycarbonates wherein a minor amountof a polyfunctional aromatic compound is coreacted with the dihydricphenol, the thiodiphenol and the carbonate precursor to provide athermoplastic randomly branched polycarbonate.

The polyfunctional aromatic compounds contain at least three frunctionalgroups which are hydroxyl, carboxyl, carboxylic anhydride, haloformyland mixtures thereof. Examples of the polyfunctional aromatic compoundsinclude trimellitic anhydride, trimellitic acid, trimellityltrichloride, 4-chloroformyl phthalic anhydride, pyromellitic acid,pyromellitic dianhydride, mellitic acid, mellitic anhydride, trimesicacid, benzophenonetetracarboxylic acid, benzophenonetetracarboxylicanhydride, and the like. The preferred polyfunctional aromatic compoundsare trimellitic anhydride or trimellitic acid or their haloformylderivatives. These and other useful polyfunctional compounds aredisclosed in U.S. Pat. Nos. 3,635,895; 4,001,184 and 4,204,047, all ofwhich are hereby incorporated herein by reference.

Also included herein are blends of a linear polycarbonate and a branchedpolycarbonate.

Rather than containing a carbonate resin which is comprised of thecoreaction products of (i) at least one dihydric phenol of Formula I,(ii) at least one thiodiphenol of Formula III, and (iii) a carbonateprecursor, the instant polycarbonate compositions may contain blends ofvarious halogen-free and sulfur-free polycarbonates and halogen-freesulfur-containing polycarbonates. Thus the instant compositions maycontain blends of (i) at least one halogen-free and sulfur-freecarbonate polymer comprised of the coreaction products of (a) at leastone dihydric phenol of Formula I, and (b) a carbonate precursor; and(ii) at least one halogen-free sulfur-containing carbonate polymercomprised of the coreaction products of (a) at least one thiodiphenol ofFormula III, and (b) a carbonate precursor.

The instant compositions may also contain blends of (i) at least onehalogen-free sulfur-containing carbonate polymer comprised of thecoreaction products of (a) at least one dihdyric phenol of Formula I,(b) at least one thiodiphenol of Formula III, and (c) a carbonateprecursor; and (ii) at least one halogen-free and sulfur-free carbonatepolymer comprised of the coreaction products of (a) at least onedihydric phenol of Formula I, and (b) a carbonate precursor.

The high molecular weight non-polycylic, halogen-free aromatic carbonatepolymers of the instant invention generally have a weight averagemolecular weight in the range of from about 5,000 to about 200,000,preferably in the range of from about 10,000 to about 100,000, and morepreferably in the range of from about 25,000 to about 50,000.

The carbonate polymers of the instant invention which are comprised ofthe coreaction products of (i) at least one dihydric phenol of FormulaI, (ii) at least one thiodiphenol of Formula III, and (iii) a carbonateprecursor contain at least two of the following repeating structuralunits: ##STR5## wherein R, R', R², R³, E, n, n', p, c and c' are asdefined hereinafore.

When, as described hereinafore, the dihydric phenol of Formula I and/orthe thidodiphenol of Formula III are coreacted with a dibasic acid acopolyester-carbonate is formed. Briefly stated, thecopolyester-carbonates of this invention comprise recurring carbonategroups, carboxylate groups, and aromatic carbocyclic groups in thelinear polymer chain, in which at least some of the carboxylate groupsand at least some of the carbonate groups are bonded directly to ringcarbon atoms of the aromatic carbocyclic groups.

These copolyester-carbonate polymers contain ester and carbonate bondsin the polymer chain, wherein the amount of ester bonds is in the rangeof from about 25 to about 90 mole percent, preferably in the range offrom about 35 to about 80 mole percent. For example, 5 moles ofbisphenol-A reacting completely with 4 moles of isophthaloyl dichlorideand 1 mole of phosgene would give a copolyester-carbonate of 80 molepercent ester bonds.

The copolyester-carbonates of the instant invention are prepared bycoreacting (i) a carbonate precursor, (ii) at least one halogen-free andsulfur-free non-polycyclic dihydric phenol of Formula I, (iii) a minoramount of at least one halogen-free thiodiphenol of Formula III, and(iv) at least one difunctional carboxylic acid or a reactive derivativethereof.

In general, any difunctional carboxylic acid conventionally used in thepreparation of linear polyesters may be utilized in the preparation ofthe instant copolyester-carbonates. Generally, the acids which may beused include the aliphatic carboxylic acids, the aromatic carboxylicacid, and the aliphatic-aromatic carboxylic acids. These acids aredisclosed in U.S. Pat. No. 3,169,121, which is hereby incorporated byreference.

The difunctional carboxylic acids which may be used generally conform tothe general formula

    R.sup.4 --R.sup.5).sub.q COOH                              VI

wherein R⁵ is an alkylene, alkylidene or cycloaliphatic groups such as acycloalkylene or cycloalkylidene group; an alkylene, alkylidene orcycloaliphatic group containing ethylenic unsaturation; and aromaticgroup such as phenylene, substituted phenylene, and the like; two ormore aromatic groups connected through non-aromatic linkages such asalkylene or alkylidene groups; and a divalent aralkyl radical such astolylene, xylelene, and the like. R⁴ is either a carboxyl or a hydroxylgroup. The letter q represents one where R⁴ is a hydroxyl group andeither one or zero where R⁴ is a carboxyl group.

Preferred difunctional carboxylic acids are the aromatic difunctionalcarboxylic acids, i.e., those acids of Formula VI wherein R⁵ representsan aromatic radical and q is one. The preferred aromatic difunctionalcarboxylic acids are represented by the general formula ##STR6## whereinR⁴ is as defined above, R⁶ is independently selected from alkylradicals, preferably those alkyl radicals containing from 1 to about 12carbon atoms; and j is a whole number having a value of from 0 to 4inclusive.

Mixtures of these carboxylic acids may be employed, and where the termdifunctional carboxylic acid is used herein it is to be understood thatthis term includes mixtures of two or more different difunctionalcarboxylic acids as well as individual difunctional carboxylic acids.

Particularly useful aromatic carboxylic acids are isophthalic acid,terephthalic acid, and mixtures thereof. A particularly useful aromaticcarboxylic acid comprises a mixture of isophthalic acid and terephthalicacid wherein the weight ratio of isophthalic acid to terephthalic acidis in the range of from about 1:10 to 10:0.

Rather than utilizing the difunctional carboxcylic acids per se, it ispossible and sometimes even preferred to employ the reactive derivativesof said acids. Illustrative of these reactive derivatives are the aciddihalides, such as the diacid halides. The preferred diacid halides arethe diacid chlorides. Thus, for example, instead of employingisophthalic acid or terephthalic acid, terephthaloyl dichloride orisophthaloyl dichloride may be employed.

The copolyester-carbonates of the present invention may be prepared byknown processes such as interfacial polymerization or phase boundaryseparation, transesterification, solution polymerization, meltpolymerization, interesterification, and the like. Various prior artpolymerization processes are disclosed in U.S. Pat. Nos. 3,030,311;3,169,121; 3,207,184 and 4,188,314, all of which are hereby incorporatedherein by reference. Although the processes may vary, several of thepreferred processes typically include dissolving or dispersing thereactants in a suitable water immiscible solvent medium and contactingthe reactants with a carbonate precursor, such as phosgene, in thepresence of a suitable catalyst and an aqueous caustic solution undercontrolled pH conditions. A molecular weight regulator, that is a chainstopper, is generally added to the reactants prior to or duringcontacting them with the carbonate precursor.

Also included herein are branched copolyester-carbonates wherein apolyfunctional compound of the type described hereinafore is acoreactant with the dihydric phenol of Formula I and the thiodiphenol ofFormula III in the reaction mixture, containing also the carbonateprecursor and the ester precursor, i.e., the difunctional carboxylicacid or a reactive derivative thereof, to provide a thermoplasticrandomly branched copolyester-carbonate resin.

The proportion of carboxylate and carbonate groups present in the finalpolymer can be suitably varied by varying the molar ratio of thedihydric phenol and thiodiphenol to difunctional carboxylic acid. Wherea dicarboxylic acid is used, it is preferable that this molar ratio ofphenol to acid be more than one. Because of the presence of hydroxylgroup in the hydroxy carboxylic acids, this preferred molar ratio doesnot apply in the case of hydroxy carboxylic acid copolymers andvirtually any ratio of phenol to hydroxy carboxylic acid may beconventionally used.

The copolyester-carbonates of the instant invention will generallycontain the following repeating structural units (when a dicarboxylicacid is used):

units of Formula IV;

units of Formula V; ##STR7## wherein R, R', R², R³, R⁵, E, n, n', p, q,c and c' are as defined hereinafore.

Rather than utilizing a single copolyester-carbonate resin blends ofcopolyester-carbonate resins may be employed in formulating the instantcompositions. Thus, for example, the instant compositions may contain ablend of copolyester-carbonate resins comprised of (i) at least onehalogen-free and sulfur-free copolyester-carbonate resin comprised ofthe coreaction products of (a) at least one dihydric phenol of FormulaI, (b) at least one difunctional carboxylic acid or a reactivederivative thereof, and (iii) a carbonate precursor; and (ii) at leastone halogen-free sulfur-containing copolyester-carbonate resin comprisedof the coreaction products of (a) at least one thiodiphenol of FormulaIII, (b) at least one difunctional carboxylic acid or a reactivederivative thereof, and (c) a carbonate precursor.

Another copolyester-carbonate resin blend is one containing (i) at leastone halogen-free and sulfur-free copolyester-carbonate resin comprisedof the coreaction products of (a) at least one dihydric phenol ofFormula I, (b) at least one difunctional carboxylic acid or a reactivederivative thereof, and (c) a carbonate precursor; and (ii) at least onehalogen-free and sulfur-containing copolyester-carbonate resin comprisedof the coreaction products of (a) at least one dihydric phenol ofFormula I, (b) at least one thiodiphenol of Formula III, (c) at leastone difunctional carboxylic acid or a reactive derivative thereof; and(c) a carbonate precursor.

The organic alkali metal salts and organic alkaline earth metal salts ofsulfonic acids useful in the instant compositions are selected from thegroup consisting of:

(A) alkali and alkaline earth metal salts of substituted andunsubstituted sulfonic acids of aromatic sulfides;

(B) alkali and alkaline earth metal salts of halocycloaliphatic aromaticsulfonic acids;

(C) alkali and alkaline earth metal salts of sulfonic acids ofheterocyclic compounds;

(D) alkali and alkaline earth metal salts of substituted andunsubstituted sulfonic acids of aromatic ketones;

(E) alkali and alkaline earth metal salts of monomeric or polymericaromatic sulfonic acids;

(F) alkali and alkaline earth metal salts of monomeric or polymericsubstituted aromatic sulfonic acids:

(G) alkali and alkaline earth metal salts of monomeric or polymericaromatic amide sulfonic acids;

(H) alkali and alkaline earth metal salts of sulfonic acids of aromaticethers;

(I) alkali and alkaline earth metal salts of monomeric or polymericsulfonic acids of aromatic carboxylic acids; and

(J) alkali and alkaline earth metal salts of monomeric or polymericphenol esters of sulfonic acids.

The alkali and alkaline earth metal salts of substituted andunsubstituted sulfonic acids of aromatic sulfides (A) are disclosed inU.S. Pat. No. 3,909,490, which is hereby incorporated herein byreference. These salts, as disclosed in said patent, can best berepresented by the formula

    R'(S).sub.1-2 R"(SO.sub.3 M).sub.1-6 (X).sub.0-11

wherein:

X is an electron withdrawing radical;

M is a metal which may be selected from the periodic table of either analkali metal or an alkaline earth metal; and

R' and R" may be either an aryl radical of 1-2 aromatic rings or analiphatic radical of 1-6 carbon atoms and they may be the same ordifferent, with the proviso that R' and R" together must contain atleast one aromatic ring. The preferred compound represented by thisformula is disclosed as being sodium4,4'-dichlorodiphenylsulfide-3-sulfonate.

The alkali and alkaline earth metal salts of halocycloaliphatic aromaticsulfonic acids (B) are disclosed in U.S. Pat. No. 3,917,559, which ishereby incorporated herein by reference.

These salts, as disclosed in said patent, are substituted aromaticsulfonic acids wherein the substituent consists of a thermally stable,halogenated cycloaliphatic radical. These salts can best be representedby the formula

    R'.sub.m (SO.sub.3 M).sub.y R"z

wherein:

R' is a halogenated cycloaliphatic radical;

R" is an aryl radical of 1-4 aromatic rings;

M is a metal which may be selected from the periodic table of either analkali metal or an alkaline earth metal;

m is an integer of 1-2;

y is an integer of 1-6; and

z is an integer of 1-2.

The preferred compound represented by this formula is disclosed as beingsodium4'[1,4,5,6,7,7-hexachlorobicyclo-[2.2.1]-hept-5-en-endo-2-yl]benzenesulfonate.

The alkali and alkaline earth metal salts of sulfonic acids ofheterocyclic compounds (C) are disclosed in U.S. Pat. No. 3,919,167,which is hereby incorporated herein by reference.

These salts can best be represented by the general formula

    X.sub.0-15 R(SO.sub.3 M).sub.1-6

wherein:

X is an electron withdrawing radical;

M is a metal which may be selected from the periodic table of either analkali metal or an alkaline earth metal; and

R is an organic nucleus selected from the group of organic heterocyclicnuclei consisting of

(i) ##STR8## wherein Z is selected from the hetero atoms consisting ofsulfur, oxygen and nitrogen,

(ii) ##STR9## wherein Z and Z' are independently selected from the groupconsisting of carbon and the hetero atoms nitrogen, sulfur, and oxygen,providing that at least one of Z or Z' is a hetero atom,

(iii) ##STR10## (iv) phthalocyanine, (v) ##STR11## and (vi) ##STR12##wherein Z is selected from the hetero atoms consisting of nitrogen,oxygen and sulfur.

The preferred compound represented by this formula is disclosed as beingthe sodium salt of 2,5-dichlorothiophene-3-sulfonic acid.

The alkali and alkaline earth metal salts of sulfonic acids of aromaticketones (D) are disclosed in U.S. Pat. No. 3,926,908, which is herebyincorporated herein by reference.

These salts, as disclosed in said patent, have the following formula:

    R'(CO).sub.1-2 R"(SO.sub.3 M).sub.1-8 (X).sub.0-11

wherein:

X is an electron withdrawing radical;

M is a metal which may be selected from the periodic table of either analkali metal or an alkaline earth metal; and

R' and R" are independently selected from aryl radicals of 1-2 aromaticrings and aliphatic radicals of 1-6 carbon atoms, provided, however,that R' and R" must contain at least one aromatic radical.

The preferred compound represented by this formula is disclosed as being4,4'-dichlorobenzophenone-3,3'-disulfonate.

The alkali and alkaline earth metal salts of monomeric or polymericaromatic sulfonic acids (E) are disclosed in U.S. Pat. No. 3,933,734,which is hereby incorporated herein by reference.

The alkali and alkaline earth metal salts of the monomeric sulfonates,as disclosed in said patent, can best be represented by the generalformula

    [A].sub.0-1 [R].sub.0-2 [B]

wherein:

A and B can, in turn, be independently selected from the followingformula

    (SO.sub.3 M).sub.y R'

where R' is an aryl radical of 1-4 aromatic rings and y is an integer of0-10, provided that the sum of y is at least one, and M is a metalselected from the group consisting of alkali metals and alkaline earthmetals; and

R is an organic radical of 1-20 carbon atoms selected from alkyl,aralkyl, alkaryl, aralkenyl, alkylene, alkylidene, aralkylidene,alkenylidene and aralkenylidene radicals.

The preferred monomeric aromatic sulfonate is disclosed as beingdisodium naphthalene-2,6-disulfonate.

The alkali and alkaline earth metal salts of polymeric aromatcsulfonates, as disclosed in this patent, can best be represented by theformula

    [A].sub.m [R.sub.1 ].sub.m+n [B].sub.n

wherein:

A and B are independently selected from

    (S0.sub.3 M).sub.y R'

where M is a metal selected from the alkali metals and the alkalineearth metals, y is an integer of 0-10, provided that the sum of y mustequal one, and R' is an aryl radical of 1-4 aromatic rings;

R₁ is an organic radical of 1-20 carbon atoms selected from arylene,alkylene, aralkylene, alkenylene, aralkenylene, alkylidene,aralkylidene, alkenylidene and aralkenylidene radicals; and

the sum of m and n must be at least 4 and can be as high as 4,000.

The alkali and alkaline earth metal salts of monomeric or polymericsubstituted aromatic sulfonic acids (F) are disclosed in U.S. Pat. No.3,940,366, which is hereby incorporated herein by reference.

The alkali and alkaline earth metal salts of the monomeric aromaticsulfonic acids, as disclosed in said patent, can best be represented bythe general formula

    [A].sub.0-1 [R].sub.0-1 [B]

wherein:

A and B are independently selected from the following formula

    R'.sub.x (SO.sub.3 M).sub.y R"

where R' is an electron withdrawing radical, M is a metal which may beselected from the periodic table of either an alkali metal or analkaline earth metal, R" is an aryl radical of 1-4 aromatic rings, x isan integer of 0-17, and y is an integer of 0-10, with the proviso thatthat the sum of x must equal at least one and that the sum of y mustequal at least one; and

R is an organic radical of 1-20 carbon atoms selected from alkyl,aralkyl, alkenyl, aralkenyl, aryl, arylene, alkylene, aralkylene,alkenylene, aralkenylene, alkylidene, aralkylidene, alkenylidene andaralkenylidene radicals.

The preferred salt of the aromatic sulfonic acids is disclosed as beingthe sodium salt of 2,4,5-trichlorobenzenesulfonic acid.

The alkali and alkaline earth metal salts of the polymeric substitutedaromatic sulfonic acids, as disclosed in this patent, can best best berepresented by the general formula

    [A].sub.m [R.sub.1 ].sub.m+n [B].sub.n

wherein:

A and B are independently selected form the following formula

    R'.sub.x (SO.sub.3 M).sub.y R"

where R' is an electron withdrawing radical, M is a metal which may beselected from the periodic table of either an alkali metal or analkaline earth metal, R" is an aryl radical of 1-4 aromatic rings, x isan integer of 0-17, and y is an integer of 0-10, with the proviso thatthe sum of x must equal at least one and that the sum of y must equal atleast one;

R₁ is an organic radical of 1-20 carbon atoms and is selected fromarylene, alkylene, aralkylene, alkenylene, aralkenylene, alkylidene,aralkylidene, alkenylidene, and aralkenylidene radicals; and

the sum of m and n must be at least 4 and can be as high as 2,000, theselection of m and n can be random or equal or one can be zero.

The alkali and alkaline earth metal salts of monomeric or polymericaromatic amide sulfonic acids (G) are disclosed in U.S. Pat. No.3,951,910, which is hereby incorporated herein by reference.

The alkali and alkaline earth metal salts of monomeric aromatic amidesulfonic acids, as disclosed in said patent, can best be represented bythe general formula

    [R].sub.z [NBB'].sub.v [NDD'].sub.w [OA].sub.t [X].sub.y [Hal].sub.u [SO.sub.3 M].sub.s

wherein:

N is nitrogen;

O is oxygen:

R, B, B', D, D' and A are organic radicals independently selected fromaliphatic and cycloaliphatic radicals of 1-20 carbon atoms and arylradicals of 1-4 aromatic rings, provided that this formula contains atleast one aromatic ring to which the [SO₃ M] substituent is attached, B,B', D, and D' are also independently hydrogen;

X is a di- or trivalent radical selected from the following: ##STR13##Hal is a halogen selected from flourine, chlorine and bromine; M is ametal which may be selected from the periodic table of either an alkalior an alkaline earth metal;

z and t are integers of 0-2, and v and w are integers from 0-4, providedthat the sum of the integers z, t, v and w is at least one;

y is an integer of from 1-4;

s is an integer of from 1-8; and

u is an integer of from 0-10.

The preferred salt of the monomeric aromatic amide sulfonic acids, asdisclosed in this patent, is the sodium salt of2,4,5-trichlorobenzenesulfonanilide-4'-sulfonate.

The alkali and alkaline earth metal salts of polymeric aromatic amidesulfonic acids, as disclosed in this patent, van best be represented bythe general formula

    ([R].sub.z [NBB'].sub.v [NBB'].sub.w [OA].sub.t [X].sub.y [Hal].sub.u [SO.sub.3 M].sub.s).sub.a --[R].sub.z [NBB'].sub.v [NBB'].sub.w [OA].sub.t [X].sub.y [Hal].sub.u [SO.sub.3 M].sub.s).sub.b

wherein:

N, O, B, B', D, D', X, M, Hal, t, u, v, w, y and z have the same meaningas specified above for the monomeric aromatic amide sulfonic acids:

a and b are integers from 2 to 300; and

s is an integer for 0-8, provided that the sum of s is at least one.

The alkali and alkaline earth metal salts of sulfonic acids of aromaticethers (H) are disclosed in U.S. Pat. No. 3,953,396, which is herebyincorporated herein by reference. These salts may be the salts of eithermonomeric or polymeric aromatic ether sulfonic acids.

The alkali and alkaline earth metal salts of monomeric aromatic ethersulfonic acids, as disclosed in said patent, can best be represented bythe general formula

    (R'O).sub.1-2 R"(SO.sub.3 M).sub.1-6 (X).sub.0-11

wherein:

X is an electron withdrawing radical;

M is a metal which may be selected from the periodic table of either analkali metal or an alkaline earth metal; and

R' and R" are independently selected from aryl radicals of from 1-2aromatic rings and aliphatic radicals of 1-6 carbon atoms, with theproviso that R' and R" together must contain at least one aromatic ring.

The preferred salt of the monomeric aromatic ether sulfonic acids isdisodium tetrchlorodiphenyletherdisulfonate.

The alkali and alkaline earth metal salts of polymeric ether sulfonicacids, as disclosed in this patent, can best be represented by thegeneral formula

    [A].sub.x [B].sub.y [ArO].sub.n [Hal].sub.s [SO.sub.3 M].sub.t H

wherein:

Ar is a phenylene radical;

O is oxygen;

A is an alkyl radical of 1-4 carbon atoms;

B is a phenyl radical;

Hal is a halogen selected from fluorine, chlorine and bromine;

M is a metal which may be selected from the periodic table of either analkali metal or an alkaline earth metal;

n is an integer of from 2 to 300;

x, y and s are integers of from 0 to 600; and

t is an integer of from 1 to 600.

The preferred alt of the polymeric aromatic ether sulfonic acids isdisclosed as being polysodiumpoly(2,6-dimethylphenyleneoxide)polysulfonate.

The alkali and alkaline earth metal salts of sulfonic acids of monomericand polymeric aromatic carboxylic acids and esters (I) are disclosed inU.S. Pat. No. 3,953,399, which is hereby incorporated herein byreference.

The alkali and alkaline earth metal salts of the unsubstituted andsubstituted sulfonic acids of monomeric aromatic carboxylic acids andesters, as disclosed in said patent, have the general formula

    X.sub.p R.sub.v (SO.sub.3 M).sub.m (COOY).sub.n R'.sub.g

wherein:

X is an electron withdrawing radical;

M is a metal selected from the alkali metals and the alkaline earthmetals;

R is an aryl radical of 1-4 aromatic rings:

R' is an organic radical of 1-4 carbon atoms selected from alkyl,alkenyl, alkylene, alkenylene, alkylidene, and alkenylidene radicals;

Y is a metal selected from alkali metals and alkaline earth metals, oran organic radical of 1-20 carbon atoms selected from alkyl, cycloalkyl,aralkyl, alkenyl, cycloalkenyl, aralkenyl, and aryl radicals;

m and n are integers of from 1 to 6;

p and q are integers of from 0 to 10; and

v is an integer of from 1 to 10.

The preferred monomeric salt of this type is sodium dimethyl2,4,6-trichloro-5-sulfoisophthalate.

The polymeric form of the sulfonic acid salts of unsubstituted andsubstituted aromatic carboxylic acids and esters can best be representedby the general formula

    [Hal].sub.p [R(COO).sub.2-4 R'].sub.m [SO.sub.3 M].sub.x

wherein:

Hal is a halogen radical selected from fluorine, chlorine and bromine:

R and R' are either aromatic nuclei of 1-4 aromatic rings or aliphaticand cycloaliphatic radicals of from 2-20 carbon atoms, providede thateither R or R' must be aromatic;

M is a metal selected from alkali metals and alkaline earth metals;

m is an integer from 2-300;

x is an integer from 1-600; and

p is an integer from 0-600.

The preferred polymeric salts of this type are polysodiumpolyethyleneterephthalate polysulfonate, polysodiumpolybutylene-2,5-dibromoterephthalate polysulfonate, and polysodiumpolybutyleneterephthalate polysulfonate.

The alkali and alkaline earth metal salts of monomeric or polymericphenol esters of sulfonic acids (J) are disclosed in U.S. Pat. No.3,978,024, which is hereby incorporated herein by reference.

The alkali and alkaline earth metal salts of monomeric phenol estersulfonic acids, as disclosed in said patent, can best be represented bythe general formula

    [R].sub.z ([O.sub.q A].sub.u [X].sub.y [O.sub.r B].sub.v).sub.m

wherein:

A and B are independently selected from the following formula

    R'(SO.sub.3 M).sub.n R".sub.p

where R' is an aromatic radical of 1-4 aromatic nuclei, M is selectedfrom alkali and alkaline earth metals, R" is an electron withdrawinggroup, n is an integer of 0 to 4, and p is an integer of 0 to 10,provided, however, that the sum of n must be at least one;

R is an organic radical of 1-20 carbon atoms and is selected from alkyl,aralkyl, alkenyl, aralkenyl, aryl, arylene, alkylene, aralkylene,alkenylene, aralkenylene, alkylidene, aralkylidene, alkenylidene,aralkenylidene, A, and B radicals;

X is selected from ##STR14## radicals; z is an integer of from 0-3;

y is an integer of from 1-2;

m is an integer of from 1-4;

q and r are integers of from 1-4;

v is an integer of from 0-4; and

O is oxygen.

The preferred metal salt of monomeric phenol ester sulfonic acid is thesodium salt of the sulfonic acid of dichlorophenyl2,4,5-trichlorobenzenesulfonate.

The alkali and alkaline earth metal salts of polymeric phenol estersulfonic acids, as disclosed in this patent, can best be represented bythe general formula

    ([R].sub.z ([A][X].sub.y [B].sub.1-3)).sub.a ([R].sub.z ([A][X].sub.y [B].sub.1-3)).sub.b

wherein:

A and B are independently selected from the following formula

    (O).sub.q R'(SO.sub.3 M).sub.n R".sub.p

where O, R', M, R", n, p and q have the same meaning as citedpreviously;

R has the same meaning as cited previously;

X has the same meaning as cited previously;

z and y have the same meaning as cited previously;

a is an integer of from 0-2,000 and b is an integer of from 0-2,000,provided however, that the sum of a and b must be at least 4 and can beas high as 2,000.

As disclosed hereinafore, the instant polycarbonate compositionscontain, in admixture:

(i) at least one halogen-free and sulfur-containing carbonate resin, ora blend of at least one halogen-free and sulfur-free carbonate resin andat least one halogen-free and sulfur-containing carbonate resin; and

(ii) a minor amount of at least one organic metal salt of sulfonic acidselected from the alkali and alkaline earth metal salts of sulfonicacids.

For the sake of clarity and convenience the term carbonate resin as usedhereinafter is meant to include the carbonate polymers and thecopolyester-carbonate polymers described hereinafore.

The halogen-free sulfur-containing carbonate resins of the instantinvention, as well as the blends of halogen-free and sulfur-freecarbonate resins and the halogen-free and sulfur-containing carbonateresins, contain an amount of sulfur which, when said carbonate resinsare admixed with the metal salts of sulfonic acids, is effective torender said compositions flame retardant. The sulfur is chemicallypresent in the halogen-free and sulfur-containing carbonate resins inthe form of the residues of the thiodiphenols of Formula III. Generally,the amount of sulfur present is in the range of from about 1 to about3.3 weight percent based on the amount of the halogen-free andsulfur-containing carbonate resin present, or based on the amount of theblend of halogen-free and sulfur-free carbonate resins and halogen-freeand sulfur-containing carbonate resins present.

This amount of sulfur is equivalent to a thiodiphenol residue content inthe polycarbonate resin, relative to the dihydric phenol residuecontent, of from about 4 to about 25 mole %.

The amount of the organic metal salts of sulfonic acids present in theinstant compositions is an amount which when combined with the amount ofsulfur present in the form of the thiodiphenol residue is effective torender the instant compositions flame retardant, but is insufficient torender said compositions opaque, i.e., an amount which is insufficientto significantly deleteriously affect the non-opaque character of theinstant polycarbonate compositions. Generally, this amount is in therange of from about 0.001 to about 0.5 part by weight per hundred partsby weight (pph) of the halogen-free polycarbonate resin present.

This combination of the alkali and alkaline earth metal salts ofsulfonic acids and the thiodiphenol has a synergistic effect upon theflame retardancy of the instant composition. That is to say, the same orgreater degree of flame retardancy can be obtained by using much smallerconcentrations of these two components in combination than by utilizingmuch larger amounts of these components separately or individually.

Thus, for example, the prior art generally discloses that compositionscomprised of an admixture of a polycarbonate resin and an organic metalsalt of sulfonic acid typically require from about 0.01 to about 10parts of the salt per hundred parts of the resin in order to be flameretardant. The instant compositions thus contain one-tenth the amount ofsalt required by the prior art.

Likewise, workers in the field have generally found that the amount ofsulfur required to render polycarbonate compositions flame retardant isin the range of from about 3 to about 15 weight percent. The instantcompositions thus generally contain about one-half the amount ofthiodiphenol disclosed as being required by workers in the field.

The instant compositions exhibit several important advantageous overprior art flame retardant polycarbonate compositions which contain muchlarger amounts of either the metal salts or the thiodiphenols. Since theinstant compositions contain much smaller amounts of the metal salts ofsulfonic acids their physical properties are not deleteriously affectedto the same degree as those of prior art polycarbonate compositions.Thus, for example, the instant compositions exhibit good impactstrength, good clarity, and good color stability.

Furthermore, since the instant compositions contain a much smalleramount of thiodiphenol, which is relatively expensive, they are muchcheaper than prior art polycarbonate compositions containing largeramounts of thiodiphenol.

Thus, the instant compositions are cheaper and posses better physicalproperties than prior art flame retardant polycarbonate compositionswhile exhibiting an equal or superior degree of flame retardancy.

The instant compositions may also optionally contain certain commonlyknown and used additives such as, for example, antioxidants; antistaticagents, inert fillers such as glass fibers, glass beads, talc, mica,clay, and the like; mold release agents; ultraviolet radiation absorberssuch as the benzophenones, benzotriazoles, benzylidene malonates, andthe like; hydrolytic stabilizers such as the epoxides disclosed in U.S.Pat. Nos. 3,489,716; 4,138,379 and 3,839,247, all of which are herebyincorporated herein by reference; color stabilizers such as theorganophosphites disclosed in U.S. Pat. Nos. 3,305,520 and 4,118,370,both of which are hereby incorporated by reference; and the like.

PREFERRED EMBODIMENT OF THE INVENTION

The following examples are presented to more fully and clearlyillustrate the invention. Although the examples set forth the best modepresently known to practice the invention they are intended to be andshould be considered as illustrative rather than limiting the invention.In the examples, all parts and percentages are by weight unlessotherwise specified.

The following examples illustrate polycarbonate compositions fallingoutside the scope of the instant invention and are presented forcomparative purposes only.

EXAMPLE 1

This example illustrates a prior art copolycarbonate which is derivedfrom bisphenol-A and thiodiphenol. This polycarbonate compositioncontains no organic alkali or alkaline earth metal salts of sulfonicacids.

Into a mixture of 2283 grams of bisphenol-A (10 moles ), 218 grams (1mole) of 4,4'-thiodiphenol, 5700 grams of water, 9275 grams of methylenechloride, 32 grams of phenol and 10 grams of triethylamine areintroduced, at ambient temperature, 1180 grams of phosgene over a periodof 97 minutes while maintaining the pH of the two-phase system at about11; i.e., pH 10-12.5, by simultaneously adding a 25% aqueous sodiumhydroxide solution. At the end of the addition period, the pH of theaqueous phase is 11.7 and the bisphenol-A content of this phase is lessthan 1 part per million as determined by ultraviolet analysis.

The methylene chloride phase is separated from the aqueous phase, washedwith an excess of dilute (0.01N) aqueous HCl and then washed three timeswith deionized water. The polymer is precipitated by steam and dried at95° C. The resultant polycarbonate is fed to an extruder, which extruderis operated at about 500° C., and the extrudate is comminuted intopellets.

The pellets are then injection molded at about 600° C. into test bars ofabout 5 in. by 1/2 in. by about 1/16 and 1/8 in. thick and into testsquares of about 2 in. by 2 in. by about 1/8 in. thick. The 1/8 in.thick test bars are subjected to the test procedure set forth inUnderwriters' Laboratories, Inc. Bulletin UL-94, Burning Test forClassified Materials. In accordance with this test procedure, materialsthat pass the test are rated V-0, V-I or V-II based on the results of 5specimens. The criteria for each V (for vertical) rating per UL-94 isbriefly as follows:

"V-0": Average flaming and/or glowing after removal of the ignitingflame shall not exceed 5 seconds and none of the specimens shall dripflaming particles which ignite absorbent cotton.

"V-I": Average flaming and/or glowing after removal of the ignitingflame shall not exceed 25 seconds and the glowing does not travelvertically for more than 1/8" of the specimen after flaming ceases andglowing is incapable of igniting absorbent cotton.

"V-II": Average flaming and/or glowing after removal of the ignitingflame shall not exceed 25 and the specimens drip flaming particles whichignite absorbent cotton.

In addition, a test bar which continues to burn for more than 25 secondsafter removal of the igniting flame is classified, not by UL-94, but bystandards of the invention, as "burns". Further, UL-94 requires that alltest bars in each test group must meet the V-type rating to achieve theparticular classification. Otherwise, the 5 test bars receive the ratingof the worst single bar. For example, if one bar is classified as V-IIand the other four are classified as V-0, then the rating for all 5 barsis V-II.

The results of these tests are set forth in Table I.

EXAMPLE 2

This example illustrates a prior art polycarbonate composition in thatthe composition contains an organic alkali or alkaline earth metal saltof sulfonic acid but the polycarbonate resin does not contain anythiodiphenol residues.

Ninety-nine parts by weight of an aromatic polycarbonate prepared byreacting bisphenol-A and phosgene in the presence of an acid acceptorand a molecular weight regulator and having an intrinsic viscosity of0.57 is mixed with one part of sodium 2,4,5-trichlorobenzenesulfonate bytumbling the ingredients together in a laboratory tumbler. The resultingmixture is then fed to an extruder, which extruder is operated at about265° C., and the extrudate is comminuted into pellets.

The pellets are then injection molded at about 315° C. into test bars ofabout 5 in. by 1/2 in. by 1/16 in. and by about 1/8 in thick. The testbars are then subjected to the UL-94 test procedure and the results areset forth in Table I.

EXAMPLE 3

The procedure of Example 2 is substantially repeated except that 99.99parts of the aromatic polycarbonate are mixed with 0.01 part of thesodium 2,4,5-trichlorobenzenesulfonate. The test bars are prepared inaccordance with the procedure of Example 2 and are subjected to theUL-94 test procedure. The results are set forth in Table I.

EXAMPLE 4

The procedure of Example 2 is substantially repeated except that sodium2,5-dichlorothiophene-3-sulfonate is substituted for the sodium2,4,5-trichlorobenzenesulfonate.

EXAMPLE 5

The procedure of Example 3 is substantially repeated except that sodium2,5-dichlorothiophene-3-sulfonate is substituted for the sodium2,4,5-trichlorobenzenesulfonate.

The following examples illustrate the preparation of the flame retardantcompositions of the instant invention.

EXAMPLE 6

The procedure of Example 1 was substantially repeated, except that thecopolycarbonate obtained in Example 1 is fed to the extruder inadmixture with 0.1 part per hundred parts by weight of sodium2,4,5-trichlorobenzenesulfonate.

EXAMPLES 7-10

The procedure of Example 6 is substantially repeated except that variousadditives and various amounts of said additives, as set forth in TableI, are substituted for the 0.1 pph of sodium2,4,5-trichlorobenzenesulfonate; and the amounts of the thiodiphenolresidue present in the copolycarbonate resin are varied, also as setforth in Table I.

EXAMPLE 11

The procedure of Example 1 is substantially repeated, except that thebisphenol-A is replaced with 2684 grams of 4,4'-cyclohexylidene diphenoland the extrusion is carried out in admixture with 0.2 parts per hundredparts of resin of sodium 2,5-dichlorobenzenesulfonate. The UL-94 ratingis found to be V-0.

EXAMPLE 12

The procedure of Example 1 is substantially repeated, except that 228grams of the bisphenol-A are replaced with 284.4 grams of4,4'-isopropylidene-3,3',5,5'-tetramethyldiphenol and the extrusion iscarried out in admixture with 0.3 pph of sodium2,4,5-trichlorobenzenesulfonate. The UL-94 rating is found to be V-0.

                                      TABLE I                                     __________________________________________________________________________    Example                                                                            BPA                                                                              TDP Mol. ratio              UL-94                                     No.  g. g.  BPA:TDP                                                                             Salt Additive pph rating                                    __________________________________________________________________________    1    2283                                                                             218 10:1  None          0   V-II                                      2    -- None                                                                              --    Sodium 2,4,5,-trichloro-                                                                    1   V-O                                                         benzenesulfonate                                            3    -- None                                                                              --    Sodium 2,4,5,-trichloro-                                                                    0.01                                                                              V-II                                                        benzenesulfonate                                            4    -- None                                                                              --    Sodium 2,5-dichlorothio-                                                                    1   V-O                                                         phene-3-sulfonate                                           5    -- None      Sodium 2,5-dichlorothio-                                                                    0.01                                                                              V-II                                                        phene-3-sulfonate                                           6    2283                                                                             108 20:1  Sodium 2,4,5-trichloro-                                                                     0.1 V-O                                                         benzenesulfonate                                            7    2283                                                                             108 20:1  Sodium 2,5-dichlorothio-                                                                    0.05                                                                              V-O                                                         phene-3-sulfonate                                           8    2283                                                                             218 10:1  Sodium 2,5-dichloroben-                                                                     0.1 V-O                                                         zene sulfonate                                              9    2283                                                                             218 10:1  Potassium diphenylsulfone-                                                                  0.05                                                                              V-I                                                         3-sulfonate                                                 10   2283                                                                             436  5:1  Sodium p-bromobenzene-                                                                      0.02                                                                              V-O                                                         sulfonate                                                   __________________________________________________________________________

As illustrated by the data in Table I the compositions of the instantinvention, Examples 6-10, exhibit a greater degree of flame retardancythan the prior art compositions, Examples 1-5. Comparing Examples 6 and7 with Example 1 it is clear that the compositions of the instantinvention exhibit a greater degree of flame retardancy than thecomposition of Example 1, even though the compositions of Examples 6 and7 are comprised of a polycarbonate resin which contains only 1/2 of thethiodiphenol residues contained by the polycarbonate resin of Example 1.

Examples 2-5 illustrate that mixing organic alkali and alkaline earthmetal salts of sulfonic acids with a halogen-free and sulfur-freepolycarbonate resin results in a flame retardant composition. However,as illustrated by a comparison of Examples 2 and 4 with Examples 3 and5, these salts must be present in relatively high concentrations inorder to render these compositions V-0. At lower concentrations of thesesalts, the resultant compositions are rendered V-II. Examples 6-10illustrate that the instant compositions can be rendered V-0 or V-I byinclusion therein of about one tenth of the amount of said salts whichbrought about the prior art compositions flame retardance of V-0.

This clearly illustrates the dramatic increase in flame retardancy ofthe instant compositions. This improvement in flame retardancy isachieved by utilizing much smaller concentrations of both thethiodiphenol and the organic alkali and alkaline earth metal salts ofsulfonic acids than employed by the prior art. Thus, when thethiodiphenol and the organic alkali and alkaline earth metal salts ofsulfonic acids are employed in combination, much lower concentrations ofthese materials need be used than if they were used separately toprovide improved flame retardancy.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained, andsince certain changes may be made in carrying out the above processesand in the compositions set forth without departing from the scope ofthis invention, it is intended that all matters contained in the abovedescription shall be interperted as illustrative and not in a limitingsense.

The use of the term nonpolycyclic refers to the group, if present, whichjoins together the two phenolic rings. That group should benonpolycylic, that is, not having two rings with at least a commoncarbon atom, such as naphthalene. The definition also excludesbridgehead compounds such as norbornyl, bicyclo(2.2.2)octane, adamantaneand the like, which are considered to be polycyclic for the purposes ofthis invention.

What is claimed is:
 1. A flame-retardant copolyester-carbonatecomposition containing, in admixture:(i) at least one halogen-free andsulfur-containing aromatic copolyester-carbonate resin derived from(a)at least one halogen-free and sulfur-free non-polycyclic dihydricphenol, (b) from about 4 to about 25 mole percent of at least onehalogen-free thiodiphenol, based on the total amount of saidhalogen-free and sulfur-free non-polycyclic dihydric phenol and saidhalogen-free thiodiphenol employed, (c) at least one difunctionalcarboxylic acid or a reactive derivative thereof, and (d) a carbonateprecursor; and (ii) an amount of at least one organic metal salt ofsulfonic acid selected from alkali and alkaline earth metal salts ofsulfonic acids which in combination with said thiodiphenol is effectiveto render said composition flame retardant.
 2. The composition of claim1 wherein said halogen-free and sulfur-containing aromaticcopolyester-carbonate resin is derived from:(i) at least onehalogen-free and sufur-free dihydric phenol; (ii) at least onehalogen-free thiodiphenol; (iii) at least one difunctional carboxylicacid or a reactive derivative thereof; and (iv) a carbonate precursor.3. The composition of claim 2 which contains an amount of saidthiodiphenol and an amount of said alkali and alkaline earth metal saltof sulfonic acid which in combination are effective to render saidcomposition flame retardant.
 4. The composition of claim 1 whichcontains from about 0.001 to about 0.5 part by weight of said alkali oralkaline earth metal salt of sulfonic acid per hundred parts by weightof said halogen-free and sulfur-containing aromaticcopolyester-carbonate resin.
 5. The composition of claim 4 whichcontains from about 4 to about 25 mole percent of said halogen-freethiodiphenol.
 6. The composition of claim 1 wherein said alkali andalkaline earth metal salt of sulfonic acid is selected from:alkali andalkaline earth metal salts of substituted and unsubstituted sulfonicacids of aromatic sulfides; alkali and alkaline earth metal salts ofhalocycloaliphatic aromatic sulfonic acids; alkali and alkaline earthmetal salts of sulfonic acids of heterocyclic compounds; alkali andalkaline earth metal salts of substituted and unsubstituted sulfonicacids of aromatic ketones; alkali and alkaline earth metal salts ofmonomeric and polymeric aromatic sulfonic acids; alkali and alkalineearth metal salts of monomeric and polymeric substituted aromaticsulfonic acids; alkali and alkaline earth metal salts of monomeric andpolymeric aromatic amide sulfonic acids; alkali and alkaline earth metalsalts of sulfonic acids of aromatic ethers; alkali and alkaline earthmetal salts of perfluoroalkyl sulfonic acids; alkali and alkaline earthmetal salts of monomeric and polymeric sulfonic acids of aromaticcarboxylic acids; and alkali and alkaline earth metal salts of monomericand polymeric phenol esters of sulfonic acids.
 7. The composition ofclaim 1 wherein said halogen-free and sulfur-free non-polycyclicdihydric phenol is represented by the general formula ##STR15## wherein:R is independently selected from monovalent hydrocarbon radicalsselected from alkyl radicals, aryl radicals, aralkyl radicals, andalkaryl radicals;R' is independently selected from monovalenthydrocarbon radicals selected from alkyl radicals, aryl radicals,aralkyl radicals, and alkaryl radicals; E is selected from non-cyclodivalent hydrocarbon radicals selected from alkylene radicals andalkylidene radicals, mon-cyclic divalent hydrocarbon radicals selectedfrom cycloalkylene radicals and cycloalkylidene radicals, the --O--radical, and the ##STR16## radical; n and n' are independently selectedfrom whole numbers having a value of from 0 to 4 inclusive; and p iseither zero or one.
 8. The composition of claim 7 wherein saidmonovalent hydrocarbon radicals are selected from alkyl radicals, arylradicals, aralkyl radicals, and alkaryl radicals.
 9. The composition ofclaim 7 wherein said monovalent hydrocarbon radicals are selected fromalkyl radicals.
 10. The composition of claim 7 wherein said non-cyclicdivalent hydrocarbon radicals are selected from alkylene and alkylideneradicals.
 11. The composition of claim 7 wherein said mono-cyclicdivalent hydrocarbon radicals are selected from cycloalkylene andcycloalkylidene radicals.
 12. The composition of claim 7 wherein E isselected from alkylene, alkylidene, cycloalkylene, and cycloalkylideneradicals.
 13. The composition of claim 12 wherein said monovalenthydrocarbon radical is selected from alkyl radicals.
 14. The compositionof claim 13 wherein p is one.
 15. The composition of claim 7 whereinsaid dihydric phenol is bisphenol-A.
 16. The composition of claim 1wherein said halogen-free thiodiphenol is represented by the generalformula ##STR17## wherein: R² is independently selected from monovalenthydrocarbon radicals selected from alkyl radicals, aryl radicals,aralkyl radicals, and alkaryl radicals;R³ is independently selected frommonovalent hydrocarbon radicals selected from alkyl radicals, arylradicals, aralkyl radicals, and alkaryl radicals; and c and c' areindependently selected from whole numbers having a value of from 0 to 4inclusive.
 17. The composition of claim 16 wherein said monovalenthydrocarbon radicals are selected from alkyl, aryl, aralkyl, and alkarylradicals.
 18. The composition of claim 16 wherein said monovalenthydrocarbon radicals are selected from alkyl radicals.
 19. Thecomposition of claim 18 wherein said thiodiphenol is selected from3,3',5,5'-tetraalkyl-4,4'-thiodiphenols.
 20. The composition of claim 16wherein said thiodiphenol is 4,4'-thiodiphenol.
 21. The composition ofclaim 1 wherein said difunctional carboxylic acid is selected fromterephthalic acid, isophthalic acid, and mixtures thereof.
 22. Thecomposition of claim 1 wherein said reactive derivatives of saiddifunctional carboxylic acids are selected from terephthaloyldichloride, isophthaloyl dichloride, and mixtures thereof.
 23. Thecomposition of claim 3 which further contains at least one halogen-freeand sulfur-free aromatic copolyester-carbonate resin.
 24. Thecomposition of claim 4 wherein said halogen-free and sulfur-freearomatic copolyester-carbonate resin is derived form:(i) at least onehalogen-free and sulfur-free dihydric phenol; (ii) at least onedifunctional carboxylic acid or a reactive derivative thereof; and (iii)a carbonate precursor.
 25. A flame-retardant copolyester-carbonatecomposition containing, in admixture:(i) at least one halogen-free andsulfur-free aromatic copolyester-carbonate resin derived from(a) atleast one halogen-free and sulfur-free non-polycyclic dihydric phenol,(b) at least one difunctional carboxylic acid or a reactive derivativethereof, and (c) a carbonate precursor; (ii) at least one halogen-freeand sulfur-containing aromatic copolyester-carbonate resin derivedfrom(a) at least one halogen-free and sulfur-free non-polycyclicdihydric phenol, (b) from about 4 to about 25 mole percent of at leastone halogen-free thiodiphenol, based on the total amount of thehalogen-free and sulfur-free non-polycyclic dihydric phenol and thehalogen-free thiodiphenol employed, (c) at least one difunctionalcarboxylic acid or a reactive derivative thereof, and (d) a carbonateprecursor; and (iii) an amount of at least one organic metal salt ofsulfonic acid selected from the alkali and alkaline earth metal salts ofsulfonic acids which in combination with said halogen-free thiodiphenolis effective to render said composition flame retardant.
 26. Thecomposition of claim 25 which contains from about 0.001 to about 0.5part by weight of said salt per hundred parts by weight of the totalamount of said halogen-free and sulfur-free aromaticcopolyester-carbonate resin and said halogen-free and sulfur-containingaromatic copolyester-carbonate resin present.
 27. The composition ofclaim 25 which is non-opaque.